CAP: causes, risk factors, pathogenesis
What organism is the most common cause of community-aquired bacterial pneumonia?
What is Streptococcus pneumoniae?
Failure of pulmonary defense mechanisms leads to inflammation that impairs this process responsible for moving air into the alveoli.
What is alveolar ventilation?
This type of cough is most commonly associated with typical bacterial pneumonia.
What is a productive cough with purulent sputum?
This procedure is performed to obtain pleural fluid for analysis.
What is thoracocentesis (thoracentesis)?
This high-dose penicillin-class antibiotic is commonly used outpatient treatment for community-acquired pneumonia.
What is amoxicillin?
These “atypical” pneumonia-causing organisms include Mycoplasma, Chlamydia, and this water-associated bacterium
What is Legionella?
This occurs in pneumonia when areas of the lung are perfused but not properly ventilated.
What is a ventilation/perfusion (V/Q) mismatch?
Unlike typical pneumonia, atypical pneumonia often presents with this type of cough.
What is a nonproductive (dry) cough?
This diagnostic tool is used to classify pleural effusions as exudative or transudative.
What are Light’s criteria?
Levofloxacin and moxifloxacin belong to this antibiotic class used to treat pneumonia.
What are respiratory fluoroquinolones?
Smoking increases pneumonia risk because it impairs this pulmonary defense mechanism responsible for clearing pathogens from the airway.
What is the mucociliary escalator?
Chronic hypoxemia from pneumonia can cause pulmonary vasoconstriction, eventually leading to these two complications.
What are pulmonary hypertension and cor pulmonale?
List the pulmonary physical exam findings of pneumonia?
What are crackles, egophony, bronchophony, dullness to percussion, and increased tactile fremitus
Name 3 conditions commonly associated with exudative pleural effusions.
What are infection, inflammation, malignancy, or autoimmune disease?
Name 4 clinical manifestations of cor pulmonale/right-sided heart failure.
What are jugular venous distention, peripheral edema, hepatomegaly, ascites, or a loud P2 heart sound?
List the 3 routes of infection.
What is microaspiration (Droplet infection) of airborne pathogens, aspiration of gastric acid/food/liquid, and hematogenous dissemination.
In this cause of hypoxemia, supplemental oxygen has little effect because blood bypasses ventilated alveoli.
“What is a right-to-left shunt?”
This type of pneumonia appears on imaging as diffuse reticular opacities without clear consolidation.
What is atypical (interstitial) pneumonia?
According to Light’s criteria, an effusion is considered exudative when the pleural fluid protein-to-serum protein ratio is greater than this value.
What is 0.5?
Compared with penicillin, ceftriaxone has enhanced bactericidal activity against many gram-negative organisms because of this...
What are beta-lactamases?
Pneumonia pathogens can spread between alveoli through these tiny interalveolar connections named after a German pathologist.
What are the pores of Kohn?
What is intrapulmonary shunting?
What is when blood passes alveoli without any ventilation, leading to inadequate oxygenation, contributing to hypoxemia in pneumonia.
A patient with pneumonia has pleuritic chest pain, decreased breath sounds, dullness to percussion, and blunting of the costophrenic angle on chest X-ray. This complication is most likely present.
What is a pleural effusion?
A patient with pneumonia has pleural fluid LDH of 250 U/L and serum LDH of 500 U/L. The lab’s upper limit of normal serum LDH is 300 U/L. Determine whether this effusion is transudative or exudative.
What is an exudative effusion?
LDH ratio = 250 ÷ 500 = 0.5, which is not > 0.6.
But 250 is greater than ⅔ of 300 = 200, so it still meets Light’s criteria for an exudate.
Explain the progression from pneumonia to cor pulmonale.
What is: pneumonia causes alveolar inflammation and hypoxemia → hypoxic pulmonary vasoconstriction increases pulmonary vascular resistance → pulmonary hypertension develops → right ventricular hypertrophy and dilation occur, leading to cor pulmonale?